Japanese researchers are claiming a breakthrough in all-optical memory, one of the key bottlenecks remaining in the optical communications world.
The high throughput of optical communications systems brings its own problem: any function that can’t be performed in the optical domain demands an opto-electric conversion, creating a …

COMMENTS

Oh dear, oh dear - you don't remember your history do you

The world's second computer - the Manchester Mark 1 (disclosure, I went to Cambridge, and so would argue vociferously that Cambridge beat Manchester in the race) - had the "William's tube" CRT memory in 1946:

Impractical. No. Multiple systems used them (IIRC the LEO commercially sold mainframe)

You're just so used to everything being in a chip you don't realize how *diverse* the history of memory systems is up until at *least* the late 1960's. Multiple mfg fought it out with various concepts for both main and register memory.

30 nanowatts you say?

Since the article also mentions a refresh time of a microsecond or so, I assume that's the ongoing cost of maintaining 1 bit of data with this new scheme. That's several hundred watts per gigabyte and a few kilowatts for a half-decent server. (Come back Pentium 4! All is forgiven!)

I know this is research and things will improve. I just though someone ought to flag up that we are several orders of magnitude short of a usable system.

Re: 30 nanowatts you say?

Doesn't really stop it being useable, it just puts an upper limit on the amount of RAM you can have if you've only got a domestic mains connection. Personally I think the more important "orders of magnitude short of a useable system" element is that they've only got four bits of optical RAM at the moment...

Re: 30 nanowatts you say?

The primary role for such a technology isn't really computing but in switching. Network switches use small quantities of RAM as buffers on the switching fabric. Without buffers on switching fabric you need a blocking infrastructure or perhaps a TDMA mechanism with an RTS signal back to the source.

If we have pure optical switching with pure optical buffers then we can have pure optical core switch fabric and provide much faster infrastructure in WANs, MANs and large offices. This is really mostly carrier grade technology, which is also why NTT is so interested.

The idea of an optical computer might be of interest to us mortals, but in the end it will be the carriers who pick this stuff up first. Much like the early computing and networking technology.

Re: A non-electric optical RAM.

Don't you remember the bid display panels that they used in Railway stations a couple of decades ago? Sure, they were electrically driven, but the actual display was a purely mechanical open/closed "flip" display. A purely mechanical version would make the difference engine look simple, but it is entirely possible.

Bubble memory

"... the optical cavity approach consumes ... 30 nW"

Thanks a lot for undoing years of scientific training by seeding my mind with the El Reg Official Units. Am I the only one whose first reaction to the statement of the title was "wait a minute, what are you doing, using a unit of surface area for reporting a measure of power??"?

Re: "... the optical cavity approach consumes ... 30 nW"

The Bleeding Obvious Optical Memory

...would be using loops of fiber. One meter will easily store 30 bits (10 Gbit/s signal rate - 3 cms per 0,1ns) per wavelength. So 100 meter would store already 30kBytes, which is already quite a bit for a high-speed switch. I don't exactly know how signal regeneration would be done, though.

Re: The Bleeding Obvious Optical Memory

Well sure yes, but you need to amplify light every couple of 10th of kilometers. You can do that optically, but not to often, since those optical amplifiers have a lot of noise. So in the end you'd have to regenerate the signal by converting it to electronic signals and then back to light... that way you loose the advantage of being all optical.

Of course photonic networks are still a pipe dream and I'm currently skeptical how useful those will be.